Predictive test for Alzheimer’s disease isn’t ready for the clinic

An international team of researchers has developed a test to help predict which patients with mild cognitive impairment will develop Alzheimer’s disease. The test combines three biomarkers in the cerebrospinal fluid—two tau proteins and the β amyloid Aβ42. The researchers used cross sectional data from 529 patients with Alzheimer’s disease and 304 healthy controls to calculate cut offs for a positive and negative test result. They then applied the cut offs to a cohort of 750 patients with mild cognitive impairment who were followed up for at least two years.

The test was reasonably accurate, predicting Alzheimer’s disease with a sensitivity of 83% (95% CI 78% to 88%) and a specificity of 72% (68% to 76%). But it is not yet ready for the memory clinic, says an editorial (p 436). Clinical and laboratory procedures have yet to be standardised, and assay results varied widely from one centre to another in this study. The trio of biomarkers could eventually be useful for screening people with mild cognitive impairment, but what would they do with the results? It is impossible to prevent Alzheimer’s disease, and no disease modifying treatments exist once it is diagnosed. A positive screening test could be distressing for patients and their relatives, and like all screening tests the result could be wrong. The study’s authors agree that for now, these biomarkers remain an experimental tool for researchers, not clinicians.

Lifestyle linked to hypertension and heart failure

The latest analyses from two well established cohorts underline once again the powerful link between lifestyle and cardiovascular health⇑. The first, a study of 83 882 US nurses, found that an estimated 78% (95% CI 49% to 90%) of incident hypertension would be prevented if all women ate a healthy diet, maintained a normal body mass index, exercised daily, drank moderately, took folic acid supplements, and used …